1. Field of the Invention
The present invention relates to a fire resistant resin composition which has less toxicity and does not damage the properties of resins.
2. Description of the Related Art
Thermoplastic resins have a property that they are easy to ignite and burn. This makes it impossible to use them as they are for uses in which it is inconvenient if they burn. Accordingly, various flameproof means are provided.
In general, thermoplastic resins are flame-proofed by blending various flame retardants. Flame retardants are divided roughly into halogen base flame retardants and non-halogen base flame retardants.
In the halogen base flame retardants, toxicity provided by acidic gas such as hydrogen bromide and hydrogen chloride produced in burning has so far been pointed out. Further, in recent years, it is regarded as a problem that there is a risk that dioxin is produced. Accordingly, attention is paid on non-halogen base flame retardants.
The non-halogen base flame retardants include, for example, metal hydroxides such as magnesium hydroxide. They have the problem that the fire resistant performance is inferior while gases produced in burning have a low toxicity as compared with halogen base flame retardants. Accordingly, in order to make thermoplastic resins fire resistant using magnesium hydroxide, it has to be blended into the resins in a large amount, and therefore the problem that the properties of the resins are damaged is caused.
Taking such background into account, the present inventors proposed previously a fire resistant composition obtained by blending a thermoplastic resin with a sulfate of a triazine compound as a non-halogen base flame retardant (Japanese Laid-Open Publication 48812/1996). Further, a fire resistant reinforced resin composition prepared by blending a thermoplastic resin with vermiculite and glass fibers is disclosed in U.S. Pat. No. 5344866. However, these compositions show a considerable fire resistant effect but the fire resistance is not satisfactory, and compositions having better fire resistance have been expected to be developed.
Further, in order to achieve a high-degree fire resistance of V-0 prescribed in UL94 Standard, the present inventors proposed a composition obtained by blending a thermoplastic resin with a sulfate of a triazine compound and thermally expandable graphite (Japanese Laid-Open Publication 81583/1996). However, this composition had the problem that it was colored black by thermally expandable graphite and could not variously be colored. Further involved was the problem that when thermally expandable graphite was blended after pulverized into fine grains in order to improve an appearance of the molded article, the thermal expanding property was lost and the sufficient fire resistance could not be obtained.
Accordingly, in a fire resistant resin composition prepared by blending a thermoplastic resin with a non-halogen base flame retardant, it has been a subject to develop a composition which has a high-degree fire resistance and is excellent in a color tone.